COIN-OR::LEMON - Graph Library

source: lemon/test/bellman_ford_test.cc @ 804:9fbbd802020f

Last change on this file since 804:9fbbd802020f was 746:75325dfccf38, checked in by Peter Kovacs <kpeter@…>, 15 years ago

Add negativeCycle() function to BellmanFord? (#51)

File size: 7.1 KB
Line 
1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2009
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#include <lemon/concepts/digraph.h>
20#include <lemon/smart_graph.h>
21#include <lemon/list_graph.h>
22#include <lemon/lgf_reader.h>
23#include <lemon/bellman_ford.h>
24#include <lemon/path.h>
25
26#include "graph_test.h"
27#include "test_tools.h"
28
29using namespace lemon;
30
31char test_lgf[] =
32  "@nodes\n"
33  "label\n"
34  "0\n"
35  "1\n"
36  "2\n"
37  "3\n"
38  "4\n"
39  "@arcs\n"
40  "    length\n"
41  "0 1 3\n"
42  "1 2 -3\n"
43  "1 2 -5\n"
44  "1 3 -2\n"
45  "0 2 -1\n"
46  "1 2 -4\n"
47  "0 3 2\n"
48  "4 2 -5\n"
49  "2 3 1\n"
50  "@attributes\n"
51  "source 0\n"
52  "target 3\n";
53
54
55void checkBellmanFordCompile()
56{
57  typedef int Value;
58  typedef concepts::Digraph Digraph;
59  typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;
60  typedef BellmanFord<Digraph, LengthMap> BF;
61  typedef Digraph::Node Node;
62  typedef Digraph::Arc Arc;
63
64  Digraph gr;
65  Node s, t, n;
66  Arc e;
67  Value l;
68  int k;
69  bool b;
70  BF::DistMap d(gr);
71  BF::PredMap p(gr);
72  LengthMap length;
73  concepts::Path<Digraph> pp;
74
75  {
76    BF bf_test(gr,length);
77    const BF& const_bf_test = bf_test;
78
79    bf_test.run(s);
80    bf_test.run(s,k);
81
82    bf_test.init();
83    bf_test.addSource(s);
84    bf_test.addSource(s, 1);
85    b = bf_test.processNextRound();
86    b = bf_test.processNextWeakRound();
87
88    bf_test.start();
89    bf_test.checkedStart();
90    bf_test.limitedStart(k);
91
92    l  = const_bf_test.dist(t);
93    e  = const_bf_test.predArc(t);
94    s  = const_bf_test.predNode(t);
95    b  = const_bf_test.reached(t);
96    d  = const_bf_test.distMap();
97    p  = const_bf_test.predMap();
98    pp = const_bf_test.path(t);
99   
100    for (BF::ActiveIt it(const_bf_test); it != INVALID; ++it) {}
101  }
102  {
103    BF::SetPredMap<concepts::ReadWriteMap<Node,Arc> >
104      ::SetDistMap<concepts::ReadWriteMap<Node,Value> >
105      ::SetOperationTraits<BellmanFordDefaultOperationTraits<Value> >
106      ::Create bf_test(gr,length);
107
108    LengthMap length_map;
109    concepts::ReadWriteMap<Node,Arc> pred_map;
110    concepts::ReadWriteMap<Node,Value> dist_map;
111   
112    bf_test
113      .lengthMap(length_map)
114      .predMap(pred_map)
115      .distMap(dist_map);
116
117    bf_test.run(s);
118    bf_test.run(s,k);
119
120    bf_test.init();
121    bf_test.addSource(s);
122    bf_test.addSource(s, 1);
123    b = bf_test.processNextRound();
124    b = bf_test.processNextWeakRound();
125
126    bf_test.start();
127    bf_test.checkedStart();
128    bf_test.limitedStart(k);
129
130    l  = bf_test.dist(t);
131    e  = bf_test.predArc(t);
132    s  = bf_test.predNode(t);
133    b  = bf_test.reached(t);
134    pp = bf_test.path(t);
135  }
136}
137
138void checkBellmanFordFunctionCompile()
139{
140  typedef int Value;
141  typedef concepts::Digraph Digraph;
142  typedef Digraph::Arc Arc;
143  typedef Digraph::Node Node;
144  typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;
145
146  Digraph g;
147  bool b;
148  bellmanFord(g,LengthMap()).run(Node());
149  b = bellmanFord(g,LengthMap()).run(Node(),Node());
150  bellmanFord(g,LengthMap())
151    .predMap(concepts::ReadWriteMap<Node,Arc>())
152    .distMap(concepts::ReadWriteMap<Node,Value>())
153    .run(Node());
154  b=bellmanFord(g,LengthMap())
155    .predMap(concepts::ReadWriteMap<Node,Arc>())
156    .distMap(concepts::ReadWriteMap<Node,Value>())
157    .path(concepts::Path<Digraph>())
158    .dist(Value())
159    .run(Node(),Node());
160}
161
162
163template <typename Digraph, typename Value>
164void checkBellmanFord() {
165  TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);
166  typedef typename Digraph::template ArcMap<Value> LengthMap;
167
168  Digraph gr;
169  Node s, t;
170  LengthMap length(gr);
171
172  std::istringstream input(test_lgf);
173  digraphReader(gr, input).
174    arcMap("length", length).
175    node("source", s).
176    node("target", t).
177    run();
178
179  BellmanFord<Digraph, LengthMap>
180    bf(gr, length);
181  bf.run(s);
182  Path<Digraph> p = bf.path(t);
183
184  check(bf.reached(t) && bf.dist(t) == -1, "Bellman-Ford found a wrong path.");
185  check(p.length() == 3, "path() found a wrong path.");
186  check(checkPath(gr, p), "path() found a wrong path.");
187  check(pathSource(gr, p) == s, "path() found a wrong path.");
188  check(pathTarget(gr, p) == t, "path() found a wrong path.");
189 
190  ListPath<Digraph> path;
191  Value dist;
192  bool reached = bellmanFord(gr,length).path(path).dist(dist).run(s,t);
193
194  check(reached && dist == -1, "Bellman-Ford found a wrong path.");
195  check(path.length() == 3, "path() found a wrong path.");
196  check(checkPath(gr, path), "path() found a wrong path.");
197  check(pathSource(gr, path) == s, "path() found a wrong path.");
198  check(pathTarget(gr, path) == t, "path() found a wrong path.");
199
200  for(ArcIt e(gr); e!=INVALID; ++e) {
201    Node u=gr.source(e);
202    Node v=gr.target(e);
203    check(!bf.reached(u) || (bf.dist(v) - bf.dist(u) <= length[e]),
204          "Wrong output. dist(target)-dist(source)-arc_length=" <<
205          bf.dist(v) - bf.dist(u) - length[e]);
206  }
207
208  for(NodeIt v(gr); v!=INVALID; ++v) {
209    if (bf.reached(v)) {
210      check(v==s || bf.predArc(v)!=INVALID, "Wrong tree.");
211      if (bf.predArc(v)!=INVALID ) {
212        Arc e=bf.predArc(v);
213        Node u=gr.source(e);
214        check(u==bf.predNode(v),"Wrong tree.");
215        check(bf.dist(v) - bf.dist(u) == length[e],
216              "Wrong distance! Difference: " <<
217              bf.dist(v) - bf.dist(u) - length[e]);
218      }
219    }
220  }
221}
222
223void checkBellmanFordNegativeCycle() {
224  DIGRAPH_TYPEDEFS(SmartDigraph);
225
226  SmartDigraph gr;
227  IntArcMap length(gr);
228 
229  Node n1 = gr.addNode();
230  Node n2 = gr.addNode();
231  Node n3 = gr.addNode();
232  Node n4 = gr.addNode();
233 
234  Arc a1 = gr.addArc(n1, n2);
235  Arc a2 = gr.addArc(n2, n2);
236 
237  length[a1] = 2;
238  length[a2] = -1;
239 
240  {
241    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
242    bf.run(n1);
243    StaticPath<SmartDigraph> p = bf.negativeCycle();
244    check(p.length() == 1 && p.front() == p.back() && p.front() == a2,
245          "Wrong negative cycle.");
246  }
247 
248  length[a2] = 0;
249 
250  {
251    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
252    bf.run(n1);
253    check(bf.negativeCycle().empty(),
254          "Negative cycle should not be found.");
255  }
256 
257  length[gr.addArc(n1, n3)] = 5;
258  length[gr.addArc(n4, n3)] = 1;
259  length[gr.addArc(n2, n4)] = 2;
260  length[gr.addArc(n3, n2)] = -4;
261 
262  {
263    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);
264    bf.init();
265    bf.addSource(n1);
266    for (int i = 0; i < 4; ++i) {
267      check(bf.negativeCycle().empty(),
268            "Negative cycle should not be found.");
269      bf.processNextRound();
270    }
271    StaticPath<SmartDigraph> p = bf.negativeCycle();
272    check(p.length() == 3, "Wrong negative cycle.");
273    check(length[p.nth(0)] + length[p.nth(1)] + length[p.nth(2)] == -1,
274          "Wrong negative cycle.");
275  }
276}
277
278int main() {
279  checkBellmanFord<ListDigraph, int>();
280  checkBellmanFord<SmartDigraph, double>();
281  checkBellmanFordNegativeCycle();
282  return 0;
283}
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